Flake fish food is easy to use. The flakes will float on the surface while the fish eat; for bottom dwelling fish, you’ll want offer food that sinks like algae wafers or pellets. Flake fish food is a good primary food source not only for the vitamins, minerals, and nutrients — flake food is easy on the digestive system. Flake food does go bad after six months or so, so those jumbo containers aren’t always a good deal. Stick to smaller containers if you can. Some of the top brands of flake foods include Aquarian, Tetra, and Wardley.
Live fish food is exactly what the name says: food that is still alive when you put it into the tank. This can include brine shrimp, daphnia, feeder goldfish, and different types of worms. Feeder fish (which are often fed to piranhas and other carnivorous fish) can introduce fish disease into the tank. Some worms are harvested from sewer areas and have a reputation for bringing disease into a tank.
Freeze dried fish food may be a safer alternative to live foods. Why? Because freeze dried foods are treated before the freeze drying process. This can kill any diseases the food may be carrying. The one drawback to freeze dried fish food is the cost — this can be the most expensive type of tropical fish food. Freeze dried foods typically contain a single animal ingredient, and can provide limited nutrients.
Frozen fish food is generally high quality, but also high in proteins and fats. Look for cube packs that will be easy to dispense, otherwise frozen fish food can be messy. Try thawing your frozen fish food a bit before adding it to the tank. Only add as much frozen fish food as your fish will eat as soon as it hits the water. Uneaten food can quickly lower your water quality. Check the label — different frozen foods include different things, like brine shrimp, beef heart, bloodworms, daphnia, krill, plankton, and more.
Vegetable diets are also available for fish. There are some fish that have long digestive tracts and can develop issues if they do not get enough roughage. But just about all tropical fish can benefit from some veggies in the diet — vegetables provide folic acid and carotenes that create red and yellow pigments in fish. Slices of par-boiled zucchini and pieces of Romaine lettuce are good vegetable supplements. Even driftwood is good for the occasional gnaw.